textproduct: Albany

SYNOPSIS

Snow showers from a clipper disturbance today continues this afternoon with lake effect and upslope enhancements in the western/southern Adirondacks and southern Greens leading to light snow accumulations this afternoon into tonight. We trend milder tomorrow through Wednesday with rain showers Tuesday afternoon into Wednesday before a more potent cold front marches through Wednesday evening. This will result in colder and windier conditions for the Thanksgiving holiday into the weekend along with increasing confidence for accumulating lake effect and upslope snow Thursday into Friday night.

SHORT TERM /THROUGH MONDAY NIGHT/

Key Message:

- Light snow accumulations through tonight for the southern and western Adirondacks and southern Greens with amounts ranging from 2 to 4 inches for elevations 1500ft+.

Discussion:

Increased warm air and moisture advection ahead of a clipper disturbance passing through to our north in Quebec has led to scattered snow showers today across areas mainly from I-90 north. The 12 UTC ALY sounding today showed plenty of dry air in the low and mid-level levels with surface dew points in the low to mid 20s and air temperatures in the low to mid 30s. Thus, as falling light precipitation has saturated the column, wet-bulb cooling processes has supported light snow falling from these showers. Areas mainly 1000ft+ have seen minor accumulations from this snow showers with much lighter intensity in valley areas and warmer ground surfaces limiting any accumulations. Areas further south in the mid- Hudson Valley and Litchfield County remain mainly south of the strongest forcing and therefore have remained drier and milder with temperatures reaching into the upper 30s to low 40s.

As the strongest warm air and moisture advection exits to our east this afternoon, snow showers coverage will decrease with temperatures even slowly warming into the upper 30s to low to mid 40s as enter in a very weak warm sector (staying colder around freezing in the southern Adirondacks and southern Greens). As the shortwave trough and sfc cold front push through by 21 to 00 UTC this evening, expecting winds to shift to the west - northwest which will usher in cooler temperatures tonight. Stronger west to northwest flow aloft and cold air advection behind the shortwave extending over the Great Lakes will help elicit a weak lake effect and upslope response for tonight. High res guidance continues to be in agreement showing bands developing off Lake Ontario that reach into the Mohawk Valley, western Adirondacks and northern Catskills with upslope developing in the northern Taconics, southern Greens and northern Berkshires starting 00 - 03 UTC. Temperatures, however, look to remain marginal in the Mohawk Valley still only in the mid to upper 30s which should keep precipitation as mainly rain or rain/snow showers during any steadier precipitation. The southern/western Adirondacks, northern Taconics, southern Greens, northern Berkshires and northern Catskills, on the other hand, should be cool in the upper 20s to low 30s supporting snow as the p-type. Therefore, these are the primary areas favored to see light snow accumulations tonight ranging from a few tenths up to 2 inches with 2 to 4 inches for areas 1500+ in elevation.

Lake effect and upslope snow diminishes by 12 UTC Monday as ridging from the Great Lakes builds eastward increasing subsidence overhead. West-northwest flow continuing will maintain cloud coverage in the typical high terrain and hill town areas through the morning. While valley areas should see more breaks of sun, westerly flow funneling down the Mohawk Valley into the Capital District should keep skies a little cloudier as forecast soundings show moisture trapped beneath subsidence inversion. However, clouds should give way to more sun Monday afternoon as ridging continue to take control. Warmer air spilling overtop the incoming ridge should also help moderate temperatures tomorrow with highs rising into the mid to upper 40s in valley areas with upper 30s in the higher terrain. We stay dry into Monday night due high pressure in place but moisture spilling overtop the ridging will cloud skies up again preventing temperatures from becoming too chilly.

LONG TERM /TUESDAY THROUGH SATURDAY/

Key Messages:

- Medium to high confidence for a period of milder temperatures Tuesday into especially Wednesday across eastern NY and western New England with a 75 - 90% chance for high temperatures on Tuesday to reach at least 45 degrees and at least 50 degrees on Wednesday.

- Increasing confidence for gusty winds Thursday into Friday across the region and accumulating lake effect snow for the Mohawk Valley and western/southern Adirondacks. There is a 40 to 70% chance for at least 4 inches of snow between 7AM Thurs and 7AM Sat in these areas with 40 to 50% chance for at least 7 inches in northern Herkimer County. Discussion:

Our period of milder weather ensues Tuesday into especially Wednesday with increasing confidence for near to above normal temperatures. Broad ridging and southwest aloft continues into Tuesday, ushering in a milder air mass with weak warm air advection also keeping skies cloudy. A weak shortwave embedded within the broad southwest flow will track northeastward Tuesday afternoon into Tuesday night, leading a period of showers. The leading edge of the strongest warm air and moisture advection continues to look delayed until 18 - 21 UTC Tues so we likely remain dry through early afternoon. Then, chances for showers increase from southwest to northeast mid to late afternoon before widespread likely and categorical POPs overspread the region by 00 - 06 UTC Wed. Luckily, temperatures remain mild enough across the area for precipitation type to remain as all rain. Rain showers decrease in coverage after Midnight but continued weak southwest flow will keep at least scattered showers in place overnight before we trend drier during the day on Wednesday. With ensemble clustering guidance in good agreement with a deepening shortwave trough over the Midwest/Upper Plains developing into a closed low over the Great Lakes by Wednesday, there is now medium to high confidence that Wednesday will be the warmest day of the week as southwest flow and downstream ridging intensify, sending a very mild air mass into the Northeast. In fact, there is a 90% chance for nearly all areas to experiences highs in the 50s with even a 50 to 70% chance for highs to exceed 55 degrees in valley areas.

However, the warm weather does not last for long as the cut-off low and occluded surface disturbance in the Great Lakes tracks eastward by Wednesday evening with its cold front marching into the Northeast. Expect a period of rain ahead of the boundary before winds shift to the west-southwest in its wake and turn breezy. Temperatures trend cooler overnight but it will take a few hours before a strong enough temperature difference between the incoming cold air mass and the Lake Erie/Ontario waters develop to elicit a lake effect response. Even when the lake effect does begin overnight Wednesday, the west-southwest wind direction looks to keep the lake effect bands directed mainly upstream of our area with only the western Adirondacks seeming impacts. In addition to the cooling temperature overnight, west to southwesterly winds will also turn breezy and turn even breezier on Thanksgiving day as cold air advection continues. In fact, latest probabilistic guidance shows 40 to 60% chance for wind gusts on Thursday to exceed 35mph across much of eastern NY and western New England. Luckily, the west- southwest wind direction will keep temperatures seasonable for late November. Otherwise, lake effect snow looks to continue to be directed in the western Adirondacks through the days.

Once the main trough axis swings through the region Thursday evening, winds likely shift to the west-northwest resulting in lake effect snow bands veering to the west-northwest and thus becoming redirected into more of the Mohawk Valley, northern Catskills and southern Adirondacks with upslope snow developing in the southern Greens. With broad troughing and cold air advection extending into the Great Lakes, a multi-lake connection may develop which would not only intensify the lake bands but also help the bands extend further east. For now, our latest forecast shows high chance and likely POPs for snow Thurs night into Friday morning limited to the Mohawk Valley and western/southern Adirondacks with chance POPS spilling further east down the I-90 corridor including the Upper Hudson Valley and southern VT. As winds continue to veer to the northwest Friday afternoon/night, lake effect bands likely shift to the northwest and become more directed into the northern/eastern Catskills with upslope continuing in the Adirondacks. Besides the lake effect snow on Friday, winds will turn even stronger on Friday given the more favorable cold air advection and northwest flow regime. There is a 30 to 70% chance for winds to exceed 40mph on Friday down the Mohawk Valley, Capital District into western New England and in the eastern Catskills. Combination of gusty winds and lake effect snow bands can also further reduce visibility on Friday.

Latest probabilistic guidance shows 40 to 80% chance for at least 4 inches of snow from the Mohawk Valley into the western Adirondacks between 7AM Thurs and 7AM Sat with a 30 to 60% chance (winter weather advisory criteria) for at least 7 inches of snow (winter storm warning criteria) in the western Adirondacks. However, exact snowfall amounts will depend on the duration, placement and intensity of the incoming lake effect snow bands. The lake effect response and gusty winds looks to finally weaken Friday night into Saturday as high pressure from the Ohio Valley builds northeastward. Northwest flow will keep temperatures seasonably cold into the holiday weekend.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

Through 18z Monday...A disturbance will continue to bring mainly scattered -SHSN to KALB/KGFL/KPSF this afternoon. The more persistent activity will be at KGFL/KPSF, where occasional MVFR/IFR vsby are expected. Will mention just occasional MVFR vsby at KALB where some downsloping should limit coverage/intensity. Most of the activity should remain north of KPOU, with just a stray -SHRA there. As temperatures warm later this afternoon, rain will mix in at KALB/KGFL with the snow showers. Coverage will decrease by 00z Sunday at most sites, but could linger in to the evening at KPSF with upslope flow there. Will mention mainly MVFR cigs this evening except IFR at KGFL and VFR at KPOU. BKN-OVC cigs should persist into Sunday morning, at borderline VFR/MVFR levels. Winds will be south- southwest around 5-10 kt today, becoming west-northwest at 5-10 tonight.

Outlook...

Monday Night: No Operational Impact. NO SIG WX. Tuesday: Moderate Operational Impact. Likely SHRA. Tuesday Night: High Operational Impact. Definite RA. Wednesday: Moderate Operational Impact. Chance of RA. Wednesday Night: High Operational Impact. Breezy. Likely RA...SN. Thanksgiving Day: Moderate Operational Impact. Windy. Slight Chance of RA...SN. Thursday Night: Moderate Operational Impact. Breezy. Chance of SN. Friday: Moderate Operational Impact. Windy. Chance of SN.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.